back fire then and beeping

[bustamove]

so i have a couple of issuses here.. old man bought a used 05 ski doo 800 151,
1400miles. ran great in the heated garage etc. got it home went to take it out found out its difficult to start and will not idle!!. dies i have to hold the throttle slightly open and then at 2rpm it back fires spits sputters.. also its beeps at me saying 10-9 which i believe is the key.. wiggle it it seems to go away.. when its running anything about 3rpm runs FANTASTIC, tons of power.

now i was checking the plugs and what not, found a knob that looks like it might turn up the idle. went to see if that would work, pulled the cord and it stops dead. the engine just stops dead in its rotation, i rotated it backwards and it will hit that one stop again... going back and forth trying to figure it out... then it started to spin freely again. pulled the cord good. pulled again good... then bam hits something play with it a bit.. didn't force it at all.... then it rotates fine... no grinding or anything.... any ideas where to start to look?

 

[xpspenziv]

possibly broke crank,broken piston ring catching inside cyl

pulled 2 cats off the mntns last year,same deal.

pull plugs look in cyl or put something in cyl long enough to stick out a
nd rotate if both don't move at same time that's bad news,shine a light in the cyl take a looksee,

pull carbs and look in int side of cyl,you can see part of piston,look for scoring and ring failure,

sound funny when it fires

is it a red knob?carb heaters

theres a phillips screw head between carbs that adjusts idle.straight up.

 

[mastertech]

I have a saying when it comes to people that like to work on there own stuff but seem to be over there head. Take it to the dealer.. For a measly 55 bucks an hr. You can get a skilled tech to diag and repair it.

 

[bustamove]

lol yeah well i bought it off a guy that does custom car for a living, he looks like hes done well. but he like yeah i just re did the clutch as well... get it home.... the belt is on backwards.. there clearly arrows on it.. i wonder what eles he put in back wards..

would a backwards piston cause idle issues?

thanks for the post xpspenziv

 

[bustamove]

so i figured it out... looks like the mag side ring caught a port.

how do you keep the rings from catching like that... this thing just had a rebuild done VERY recently.

 

[sledsrock]

Piston in backwards? Ring locating pin is gone? The ring locating pins do just that, locate the ring on the piston so they will not spin and catch a port. Bad or lack of port chamfering also will cause this.

 

[bustamove]

piston is put in properly. not sure about the locater pin as i just took the head off for now.

lack of port chamfering?... maybe should i lightly sand the ports at a 45 on the edges?

 

[gus bohne]

If the enigne was ported wrong the ring gap might be in the edge of a transfer port.
If it is you need a weld and replate to repair.
If it is NOT ported and piston was installed correctly, my question would be WHY was it just rebuilt?

It is very vewry hard to buy that it was just running for a few moments and bang.. more likely,, it was a ring that got snagged on the bottom of the cylinder when it was assembled, or the cylnder was not straight when the piston was slid in, then when the cylinder was rotated the ring caught on the bottom scallop cut and was broken or bent baddly.

I see this a few times a year. the chassis is tight, the installer doesnt realize the ring is hurt by twising the cylinder around..its not a no no but if you feel resistance ...STOP.. most dont they force ..


Gus

 

[bustamove]

so i got a little more info... the reason he did a top end before was cuz it blew up on the mag side... he replaced both pistons and mag side cylinder.. apparently it was installed by a ex ski doo dealer mechanic.

the mag side is the one that went again... would a bent crank cause this... why would it go again? what can i do to keep it from doing this again?

is it worth going to a MCB dual piston ring set up? can i run the stock head?